Swine flu in humans in the USA and Mexico

An advisory from Singapore's AVA

USA and Mexico had reported cases of flu in humans caused by a new Swine Influenza A/H1N1 virus that contains a reassortment of gene segments from different strains of avian, porcine (pig) and human flu viruses. According to the US Centers for Disease Control and Prevention (CDC), the virus characterised in this outbreak has not been previously recognised in the USA or elsewhere. The World Health Organization (WHO) also states that the virus has not been previously detected in pigs or humans.

The Agri-Food & Veterinary Authority of Singapore (AVA) would like to assure the public that it is closely monitoring this developing situation, which started in the USA and Mexico, and is taking the necessary measures to safeguard the public health in Singapore.

Swine flu in pigs
In pigs, swine flu is a respiratory disease and the infection usually affects only the respiratory tract. The disease is commonly found in major pig-producing countries. However, most of the swine influenza virus strains are usually not transmissible to humans. The lungs are the major target organs in an infected animal. Swine flu virus particles are not found outside the respiratory tract and associated lymph nodes.

Virus spread by human-to-human contact
Previously, there had been reports of swine flu in humans which were spread in the following two ways:
•Through contact with infected pigs or environments contaminated with swine flu viruses.
•Through contact with a person with swine flu i.e. human-to-human spread

 In the current situation in the US, CDC has determined that the virus was spread through the human-to-human mode. The human cases in the US did not have contact with pigs and the US authorities have also not reported infection in pigs caused by the same viral strain.

No danger of contracting flu virus from imported pork
According to the US CDC and WHO, swine flu viruses are not spread by food. Humans cannot get swine flu from eating pork or pork products. Eating properly handled and cooked pork products is safe. Cooking will render the pork safer, as cooking would kill any flu viruses.

Singapore does not import pork from Mexico, as Mexico is not an approved country for exporting pork and pork products to Singapore. Singapore has imported 2,700 tons of frozen pork and other pork products from the USA since the beginning of 2009. There is no import of chilled pork from the USA. During the same period, Singapore only imported processed pork products from the affected US states of California, Texas and Kansas. Properly heat processed products do not pose a risk of swine flu virus. US pork constitutes about 10% of total imported pork and pork products to Singapore. There is also no import of pig lungs into Singapore from any country in the last three years.

Even though there is no danger of contracting swine flu from pork, AVA will test incoming pork imports from the US as well as other sources for flu virus as a precautionary measure.

Imported pigs
Singapore does not import pigs from the USA. Singapore only imports pigs from one AVA-accredited farm located on Pulau Bulan, Indonesia. There is no introduction of pigs from external sources into the farm and it maintains a high level of biosecurity, including strict access of people into the farm and implementing rigorous hygiene and sanitation practices. Pigs in the farm are also regularly vaccinated against swine influenza. AVA inspects the farm regularly to ensure that it implements its biosecurity measures and closely monitors the on-farm disease situation as well as the health of the pigs imported from the farm into Singapore.

The imported pigs are slaughtered in the single pig abattoir in Singapore. The abattoir is regulated by AVA, with inspectors checking on the health of the animals throughout its process, from pre-slaughter to cutting. Although pigs from the farm present a low risk of transmitting swine influenza to humans, AVA has also taken further precautionary measures by requiring abattoir workers and AVA staff, who have contact with pigs to don protective attire, such as face shield and protective clothes. As a standard operating procedure, all lungs are removed for destruction and do not enter the food supply.

AVA will also step up surveillance testing of the pigs from Pulau Bulan to ensure that they are not infected with the virus found in the current outbreaks.

Monitoring of situation

AVA is monitoring the Swine Influenza situation closely and will take all necessary measures, if there is clear evidence of involvement of pigs or pork in the transmission. AVA is already in contact with its counterparts in the US, and will also work closely with MOH and other authorities on this aspect.